Electric current and voltage indicator



R. W. ELLIOTT ELECTRIC CURRENT AND VOLTAGE INDICATOR May 3@, I950 Filed July 24, 1945 INVENTOR. oss w ELLIOTT BY Patented May 30, 1950 iti'ifhi) STATES 1 Claim. 1

My invention relates to an electric current and voltage: indicator, more particularly of the-sportable type adapted to be carried on the: person of an electrician or other. service man. and the objects of my invention are:

First, to provide an instrument of this class which indicates actual values of current and voltage without the-useof a delicate and expensive meter;

Second, to providean-instrument of this class in which an electronictube is used and so arranged that it will operate at the ignition point indicating voltage or current in accordance with ad. iustment a variable resister forming a part of" said instrument;

Third, to provide n instrument of this class in which an automatic reset protects it from over loads to which it may be subjected inadvertently;

Fourth, to provide an instrument of this class in which all of the exterior portions are properly insulated for the protection of the operator;

Fifth, to provide an instrument of this class which is very compact, light in weight nd very durable;

Sixth, to provide an instrument of this class which will provide safety to men working at the various electrical trades; and

Seventh, to provide an instrument of this class which is very simple and economical of construction, efiicient in its action and which will not 5,11

readily deteriorate or get out of order.

With these and other objects in View as will appear hereinafter, my invention consists of certain novel features of construction, combination and arrangement of parts and portions as will be hereinafter described in detail and particularly set forth in the appended claim, reference being had to the accompanying drawings and to the characters of reference thereon forming a part of this application in which:

Figure 1 is a side elevational view of my electric current and voltage indicator showing portions thereof broken away and in section to amplify the illustration and further showing by dash lines varying positions of parts and portions thereof; Fig. 2 is an edge elevational view thereof and Fig. 3 is a schematic view of the wiring of my electric current and voltage indicator.

Similar characters of reference refer to similar parts and portions throughout the several views of the drawings:

The casing members i and 2, transformer portions 3 and 4, rheostats 5, voltage conductors 5 and 1, resisters 8 and 9, neon tube H3, control knob H and transformer control spring 12 con- 2 stitute; the: principal parts andaportionse of: my electric current and: voltage indicator.

The casi'hg members I: and 2 aremade of insulation mateniat and the casingmember I} is the boxlike casing in which is :rigidly. mounted the transfor-merwportion 3i having an L-shaped'. laminated core 3a engageable with the: laminated core 4a of the transformer'portion: 4 which is rigidly connectedito theicasing member 2. This casing member 2 forms the side edge ofimyl electric current and voltage indicator and this .casing member 2 is sl'iiftableas indicated by: dash lines in Fig.- 1 of thedrawings. The core portion th ef" the transformer portion 4' is L-shaped" and the end portion ib thereof is' shiftably" mounted in'the' frame portion Sb about theinner end of the core portion 3a of the transformer it. It will be noted that the end portion 4b of the core portion 4a engages the end portion 30 of the core portion 3a and that the spring 12 maintains the end portion 4b and 3c in engaged relation to each other, thus pressure exerted on the upper end portion 2a of the casing member 2 causes the transformer portion 4, together with the casing member 2 to pivot, as shown by dash lines in Fig. 1 of the drawings separating the contact ends 40 and 3d of the transformer portion cores 4a. and 3a respectively.

Referring now to the wiring diagram in Fig. 3 of the drawings, the voltage conductors 6 and I are connected to mixed resisters 8 and L! respec tively which have a value of approximately seventy-five thousand ohms. In circuit with these resisters 8 and 9 is the rheostat 5 which is a two megohms variable resister rotatively operated by the control knob H on which are the voltage and ampere scales cooperating with the pointer 2 ia secured on the casing i.

The neon tube I0 is placed behind a window lila in the said wall of the casing I as shown best in Fig. 1 of the drawing and is in circuit with the windings of the core portions 3a and 4a of the transformer portions 3 and 4, as shown in Fig. 3 of the drawings.

It will be here noted that the transformer portions in cooperative relation, as shown, forma split core transformer.

The operation of my electric current and voltage indicator is substantially as follows: Assuming that an electrician wishes to read the current in amperes, the portion 2a of the casing, 2 is depressed causing the core portion 4a of the transformer portion 4 to shift to the dash line position, as shown in Fig. 1 of the drawings, permitting the insertion of the wire A between the ends 40 and 3d of the core portion 4a and 30 respectively, as shown in Fig. 1 of the drawings. When the wire A is so positioned, the transformer control spring [2 forces the core portion 3a and 4a together forming a core path for the magnet field around the wire A. In order to indicate the current passing in connection with the wire A the control knob I I is turned clockwise until the neon tube H] glows through the window Mia. The amperage is then read directly at the point on the indicator Ila in connection with the amperage scale on the control knob ll. When it is desired to make a test for voltage, the voltage conductors 6 and I are connected to the circuit in question and the control knob II is turned clockwise until the neon tubes Ill glow, then the voltage is read directly at the point of the indicator la on the voltage scale on the control knob l I.

Though I have shown nd described a particular construction, combination and arrangement of parts and portions, I do not wish to be limited to the particular construction, combination and arrangement, but desire to include in the scope of my invention the construction, combination and arrangement substantially as set forth in the appended claim.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

In an electric current and voltage indicator of the class described, the combination of a casing, a split core current transformer having core portions therein pivotally mounted relatively to each other, each of said casings having an extending laminated core portion engageable with each other, a spring tending to force the extended portions of said core portions together, a variable resistor in circuit with the windings of said core portions across conductors thereto, a control knob in connection with said variable resister having calibrations thereon and arranged to actuate the movable contact of said variable resistor, a neon tube connected across said variable resister and said core portions, said neon tube intermediate said variable resistor and said transformer core portions for indicating the ignition point common to the amperage value of current passing in connection with the wire inserted between said extending core portions of said transformer, voltage conductors and fixed resisters in connection with said voltage conductors in circuit with said variable resisters and said transformer core portions.

ROSS W. ELLIOTT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,918,834 Crago July 18, 1933 1,924,039 Hockley Aug. 22, 1933 1,965,151 Mueler July 3, 1934 2,146,555 Arey Feb. 7, 1939 FOREIGN PATENTS Number Country Date 313,208 Great Britain June 10, 1929 346,926 Great Britain Apr. 23, 1931 

